Edward h



(No Model.) Y E. H. JOHNSON.

ELECTRICAL GONDUGTR.

Patented Mar. 22., l1887.

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N. PETERS, Phn\ol.imugrnphur, washingmn. Dc.

UNITED STATES PATENT OFFICE.

EDVARD H. JOHNSON, OF NEV YORK, N. Y.

ELECTRICAL CONDUCTOR.

SPECIFICATION forming part Of Letters Patent No. 359,726, dated March 22l 1887.

Application filed August i3, 1884. Serial No. 140,410.

To all whom it may concern:

Be it known that I, EDWARD H. JOHNSON, of New York city, in the county and State of New York, have invented a certain new and useful Improvement in Electrical Conductors, of which the following is a specification.

The object I have in view is to produce a method of arranging and insulating electrical conductors, more especially adapted and designed for wiring houses, ships, and other structures for the electrielight and the wiring of xtures for supporting incandescent electric lamps,which will make it possible, by the employment of fusible safety-catches, to prevent absolutely the setting of fires by leakage of the current.

Heretofore it has been considered conducive to safety to separate the two conductors of an electric-light `circuit a considerable distance; but experience has shown that when this is done leaks between the conductors will occur through intervening material, which may be ignited by the formation of a high-resistance are without fusing the safety-catches designed to protect the circuit. I have discovered, however, that by bringing the conductors close together, and so arranging and constructing them that any imperfection of the insulation will immediately establish an are between the conductors themselves of such low resistance as to amount to a practical short circuit, the safety-catches will be invariably fused and the circuit broken before damage can occur.

The mostperfect insulators of electricity known to the art, and those that ,are proof against moisture, are oils or gums which are inflammable; but by the methods heretofore employed forinsulating the separated conductors it has been found impracticable to use these more perfect and water-proof insulations on account of theirinammability, and noncombustible insulating-coverings have been employed, which, by reasonof being less perfect insulators, permit the formation of dangerous leaks.

My method makes it possible to insulate the conductors from each other by the most perfeet water-proof materials for the purpose, regardless of their inflammable nature, and also to employ the non-inflammable insulations between the conductors and the structure upon which the conductors are supported, and where their inferior insulating properties are of less (No model.)

that it is convenient to make the connections required ,in ruiming circuits.

In carrying out my invention I produce a compound conductor having the two conductors of a complete or round metallic cir cuit inclosed in a common insulating-covering, which is a non-infiammable insulation of any suitable character, such as a braided, woven, or knit cotton covering impregnated with white lead or other non-inflammable material. lVithin this covering the conductors are arranged so that one forms a complete metallic shield for the other, and the two conductors are separated by the most perfect waterproof insulation, without regard to itsI infiammable nature, such as paraftine or rubber, or other moistureexcluding material, such as bitumen or a fabric impregnated with these or any other material of this nature.

The core of the compound conductor is a wire or a bundle of wires covered carefully with the paraffine, rubber, or similar insulation. The other conductor is composed of a number of bare wires of such a size that they can be placed over the inner conductor and its insulation, and will form a complete metallic shield7 and at the same time will have the same or approximately the same currentconducting capacity as the inner conductor. rlhese naked wires are preferably wound spirally upon the inner insulated conductor in one layer, the spiral winding being preferred to prevent kinking in use, although the wires composing the outer conductor may be laid parallel with the inner conductor.

Instead of using a number of wires for the outer conductor, it may be composed of one or more flat strips wound spirally upon the inner insulated conductor, and forming a complete metallic shield for the same. By reason of the arrangement of the outer conductor as a shield for the inner conductor, said outer conductor must necessarily have a less thick ness at any one point than the inner conductor, and it might be possible for the current in arcing between the conductors to blow a hole through the outer conductor without fusing the safety-catch, resulting in weakening the outer conductor at that point and causing it to be heated by the current, which continues to flow. This objection to the arrangement of the conductors described I overcome by interposing between the outer and inner conductors, and in contact with the outer conductor, a thin body of metal the fusing-point of which is lower than that of copper. This thin body of metal may be a lead covering` placed upon the insulation of the inner conductor in any of the known ways of covering insulated wire with lead. It is preferably quite thin, and should hug the insulation of the inner conductor closely, and this insulation of' the inner conductor is also preferably as thin as it can be made practically. The body of easily-fusible metal, instead ot' heilig a solid tube of lead, as usual in covering wire with lead, might be made of lead or tin-foil wound upon the insulation of the inner conductor. The bare wires forming the outer conductor are laid directly upon this lead covering, which in the areing of the con ductors fuses before the copper, and forms an are of the required low resistance to fuse the safety-catches. After the lead covering and the outer conductor are placed upon the inner insulated conductor, the whole is covered, as before explained, by a non-inflammable insulation, such as a cotton covering impregnated with white lead or other tire-proof material.

The compound conductor is lused with fusible safety-catches placed in one or in each side of the circuit at the points of departure of smaller from larger conductors.

It will be seen that there can be no contact of the inner conductor with any external object except through the outer conductor. The breaking down of the insulation separating the conductors will with certainty produce an arc of such low resistance as to effect a short circuit between the conductors, instantly fusing the safety-catch or safety-catches protecting the particular conductors, and breaking the circuit, or the two conductors, being in such close proximity, will be soldered together by the fusion of the lead covering, which evidently will form a short circuit between them.

My compound conductor also possesses the advantage of cheapening to a large extent the cost of wiring houses and other structures for electric light, since provision only has to be made for one conductor7 and the labor is equivalent to the' running of one conductor only. For wiring fixtures, and especially combination gas and electric-light fixtures, the impossibility of forming an are between the conductors and outside material-as the metal ofthe iXture-removes a constant danger, which has heretofore been an obstacle in the way of fixture-work.

In making connect-ions with the compound conductor the outer conductor is unwound from the inner conductor to the desired ex! tent and the inner conductor laid bare. lThe wires forming the outer conductor can be twisted together by hand, and a good and sccure electrical and mechanical connection can be made with them.

In the accompanying drawings, forming a part hereof, Figure 1 is an elevation ofthe compound conductor partially stripped to show its construction; Fig. 2, a cross-section, on a larger scale, of the compound conductor; and Fig. 3, a view showing the conductor in use.

A is the inner conductor. I is the high water-proof insulation of parat-line, rubber, or

similar material, placed thereon. O is the lead covering ot the inner conductor. D is the outer conductor arranged to shield mcchanically the inner conductor, and E is thc tire-proof insulation forming the outer covering for the compound conductor. y

Referring to Fig. 8, the compound conductors 1, 2, and 3 are shown as joined in an electric-light circuit. 1 is larger than 2 and 3, which form branches ofi. At the point of departure of the smaller from the larger conductors the fusible safety-catches (t b are introduced into the circuit. These are proportioned to protect 2 and S. 1 is protected by fusible safety-catches where it branches from larger conductors or at the dynamo-machine, ifit proceeds directly therefrom.

1. A compound electrical conductor having, in combination, an inner conductor, an outer conductor surrounding the inner conductor and insulatedtherefrom,and a body of readilyfused metal interposed between the conductors, substantially as set forth.

2. A compound electrical conductorliaviiig, in combination, an inner conductor covered with insulation, a covering of an easily-fused metal upon such insulation, and an outer conductor in contact with said easily-fused metal covering, substantially as set forth.

3. The combination, in a tlexible compound conductor, of an inner insulated conductor, a covering thereon of an easily-fused metal, and an outer conductor composed of a number of wires, substantially as set forth.

4. The combination, with two conductors, of a complete or round metallic circuit, one of which surrounds and formsa shield for the other, and the two conductors being situated in soldering proximity to each other, of a fusible safety-catch in the circuit,substantial! y as set forth.

5. The combination, in an electrical circuit, with an insulated inner conductor, an outer in closing-conductor, and a body of easily-fused metal between the two conductors, oi' a fusible safety-catch, substantially as set forth.

This speciiication signed and witnessed this Sth day of August, 1884.

EDVARD H. JOHNSON.

Witnesses:

Wit. H. Mniinowcnorr, A.. W. KrnnLu.

ICO 

